GHSA-86WV-8X6P-4RHG

Vulnerability from github – Published: 2026-05-05 18:33 – Updated: 2026-05-05 18:33
VLAI?
Details

In the Linux kernel, the following vulnerability has been resolved:

ext4: always drain queued discard work in ext4_mb_release()

While reviewing recent ext4 patch[1], Sashiko raised the following concern[2]:

If the filesystem is initially mounted with the discard option, deleting files will populate sbi->s_discard_list and queue s_discard_work. If it is then remounted with nodiscard, the EXT4_MOUNT_DISCARD flag is cleared, but the pending s_discard_work is neither cancelled nor flushed.

[1] https://lore.kernel.org/r/20260319094545.19291-1-qiang.zhang@linux.dev/ [2] https://sashiko.dev/#/patchset/20260319094545.19291-1-qiang.zhang%40linux.dev

The concern was valid, but it had nothing to do with the patch[1]. One of the problems with Sashiko in its current (early) form is that it will detect pre-existing issues and report it as a problem with the patch that it is reviewing.

In practice, it would be hard to hit deliberately (unless you are a malicious syzkaller fuzzer), since it would involve mounting the file system with -o discard, and then deleting a large number of files, remounting the file system with -o nodiscard, and then immediately unmounting the file system before the queued discard work has a change to drain on its own.

Fix it because it's a real bug, and to avoid Sashiko from raising this concern when analyzing future patches to mballoc.c.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43065"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-05T16:16:15Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: always drain queued discard work in ext4_mb_release()\n\nWhile reviewing recent ext4 patch[1], Sashiko raised the following\nconcern[2]:\n\n\u003e If the filesystem is initially mounted with the discard option,\n\u003e deleting files will populate sbi-\u003es_discard_list and queue\n\u003e s_discard_work. If it is then remounted with nodiscard, the\n\u003e EXT4_MOUNT_DISCARD flag is cleared, but the pending s_discard_work is\n\u003e neither cancelled nor flushed.\n\n[1] https://lore.kernel.org/r/20260319094545.19291-1-qiang.zhang@linux.dev/\n[2] https://sashiko.dev/#/patchset/20260319094545.19291-1-qiang.zhang%40linux.dev\n\nThe concern was valid, but it had nothing to do with the patch[1].\nOne of the problems with Sashiko in its current (early) form is that\nit will detect pre-existing issues and report it as a problem with the\npatch that it is reviewing.\n\nIn practice, it would be hard to hit deliberately (unless you are a\nmalicious syzkaller fuzzer), since it would involve mounting the file\nsystem with -o discard, and then deleting a large number of files,\nremounting the file system with -o nodiscard, and then immediately\nunmounting the file system before the queued discard work has a change\nto drain on its own.\n\nFix it because it\u0027s a real bug, and to avoid Sashiko from raising this\nconcern when analyzing future patches to mballoc.c.",
  "id": "GHSA-86wv-8x6p-4rhg",
  "modified": "2026-05-05T18:33:25Z",
  "published": "2026-05-05T18:33:25Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43065"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c82f863f090ab899085bdfade073313384b514b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/812b6a7cd3e7f3a3e8a24db85bc6313c26cb1098"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9b4d9dda6a71ad3425c8109d27c4c6bfb9da97b8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9ee29d20aab228adfb02ca93f87fb53c56c2f3af"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b4737e26d4688b8aea88ad6ea4dbfeb6e78b0327"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c360e9d0def4f4ae03254a67c683103908555b75"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e96c2354b170aaa53300c8e8fd59e41b133160f7"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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